Tony Nelson

ou non, manant des tablissements d'enseignement et de recherche franais ou trangers, des laboratoires publics ou privs.

SHERLOC is an arm-mounted fluorescence and Raman spectrometer that was recently selected to be part of the payload for the next proposed NASA rover mission to Mars, scheduled for launch in 2020. SHERLOC enables non-contact, spatially resolved, high sensitivity detection and characterization of organics and minerals on the Martian surface. The investigation goals are to assess past aqueous history, detect the presence and preservation potential of biosignatures, and support the selection of samples for caching and potential return to Earth.

Over the past 15 years many organizations have researched the use of Static-Random Access Memory (SRAM)-based Field-Programmable Gate Arrays (FPGAs) in space. Although the components can provide a performance improvement over radiation-hardened processing components, random soft errors can occur from the naturally occurring space radiation environment. Many organizations have been developing methods for characterizing, emulating, and simulating radiation-induced events; mitigating and removing radiation-induced computational errors; and designing fault-tolerant reconfigurable spacecraft. Los Alamos National Laboratory has fielded one of the longest space-based FPGAs experiments, called the Cibola Flight Experiment (CFE), using Xilinx Virtex FPGAs. CFE has successfully deployed commercial SRAM FPGAs into a low-Earth orbit with Single-Event Upset (SEU) mitigation and was able to exploit effectively the reconfigurability and customization of FPGAs in a harsh radiation environment. Although older than current state-of-the-art FPGAs, these same concepts are used to deploy newer FPGA-based space systems since the launch of the CFE satellite and will continue to be useful for newer systems. In this article, we present how the system was designed to be fault tolerant, prelaunch predictions of expected on-orbit behaviors, and on-orbit results.

AEGIS (Autonomous Exploration for Gathering Increased Science) is a software suite that will imminently be operational aboard NASA's Curiosity Mars rover, allowing the rover to autonomously detect and prioritize targets in its surroundings, and acquire geochemical spectra using its ChemCam instrument. ChemCam, a Laser-Induced Breakdown Spectrometer (LIBS), is normally used to study targets selected by scientists using images taken by the rover on a previous sol and relayed by Mars orbiters to Earth. During certain mission phases, ground-based target selection entails significant delays and the use of limited communication bandwidth to send the images. AEGIS will allow the science team to define the properties of preferred targets, and obtain geochemical data more quickly, at lower data penalty, without the extra ground-inthe-loop step. The system uses advanced image analysis techniques to find targets in images taken by the rover's stereo navigation cameras (NavCam), and can rank, filter, and select targets based on properties selected by the science team. AEGIS can also be used to analyze images from ChemCam's Remote Micro Imager (RMI) context camera, allowing it to autonomously target very fine-scale features - such as veins in a rock outcrop - which are too small to detect with the range and resolution of NavCam. AEGIS allows science activities to be conducted in a greater range of mission conditions, and saves precious time and command cycles during the rover's surface mission. The system is currently undergoing initial tests and checkouts aboard the rover, and is expected to be operational by late 2015. Other current activities are focused on science team training and the development of target profiles for the environments in which AEGIS is expected to be used on Mars.